Mozilla plans to ship a beta of Firefox 4 next month, and a final by the end of November, a company executive said yesterday.

In a 50-minute presentation, Mike Beltzner, the director of Firefox, spelled out not only the timeline for the next major upgrade, but also outlined the new features, changes and technology enhancements the company hopes to pack into the browser.

Beltzner also confirmed that Mozilla has dropped the idea of doing an interim edition, Firefox 3.7, which at one point last year it had slated for a mid-2010 release. Instead, the next version of Firefox 3.6 will include the primary feature once scheduled for Firefox 3.7, technology that splits some plug-in processes from the core browser.

That technology and associated project, dubbed "Lorentz," prevents crashes by Adobe's Flash, Apple's QuickTime or Microsoft's Silverlight plug-ins from bringing down the browser. The so-called "out of process plug-ins," or OOPP as Mozilla calls the feature, will officially debut when Firefox 3.6.4 launches Thursday.

Most of Beltzner's presentation, which was Webcast live Monday afternoon and is also available in a recorded version (HTML5 video-enabled browser, such as Firefox 3.6, required), was dedicated to defining the goals Mozilla has for Firefox 4, down to the individual features that may or may not make it into the final.

Performance is one of the key areas Firefox 4 will address, said Beltzner. "Performance is a huge, huge, huge thing for us," he said. "We created the performance story, and we've got to keep at it."

Beltzner emphasized that Mozilla will both boost the raw speed of Firefox -- it has been working on ways to push its TraceMonkey JavaScript engine -- and in users' perception of speed.

The latter will be tackled by slimming down Firefox's user interface, something Mozilla has been working on since last year. "The simpler an interface looks, the faster it will seem," said Beltzner. "The less the user has to take in with their eye, the quicker they can process it and the quicker the entire application will seem. So we're actually looking at making our interface faster just by changing the way it looks."

Mozilla's timeline shows plans to issue a Firefox 4 beta in June and make a final version by November. (Photo courtesy of Mozilla Corp.)

The new interface for Firefox 4 will remind many of Google's Chrome, with tabs above the toolbar and address bar, fewer buttons -- including an all-in-one Home button that also serves as a single-menu App button -- and fewer dialog box interruptions. Mozilla is also aiming to eventually emulate Chrome by applying updates silently in the background.